n = int(input())
a = list(map(int, input().split()))
s = sum(a)

total = 0
t = n//2 if n % 2 == 0 else n//2+1

total = s*n
df = 0
for i in range(1, t):
    df += a[i-1] + a[-i]
    total += (s - df) * (n-2*i)

print(total)